{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,22]],"date-time":"2026-04-22T18:18:23Z","timestamp":1776881903211,"version":"3.51.2"},"reference-count":42,"publisher":"AIP Publishing","issue":"4","funder":[{"DOI":"10.13039\/100019784","name":"EUROfusion","doi-asserted-by":"publisher","award":["101052200"],"award-info":[{"award-number":["101052200"]}],"id":[{"id":"10.13039\/100019784","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000266","name":"Engineering and Physical Sciences Research Council","doi-asserted-by":"publisher","award":["EP\/W006839\/1"],"award-info":[{"award-number":["EP\/W006839\/1"]}],"id":[{"id":"10.13039\/501100000266","id-type":"DOI","asserted-by":"publisher"}]},{"name":"EUROfusion Enabling Research Project","award":["ENRTEC.01.IST"],"award-info":[{"award-number":["ENRTEC.01.IST"]}]}],"content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2024,4,1]]},"abstract":"<jats:p>JET\u2019s frequency-modulated continuous wave (FMCW) reflectometers have been operating well with the current design since 2005, and density profiles have been automatically calculated intershot since then. However, the calculated profiles had long suffered from several shortcomings: poor agreement with other diagnostics, sometimes inappropriately moving radially by several centimeters, elevated levels of radial jitter, and persistent wriggles (strong unphysical oscillations). In this research, several techniques are applied to the reflectometry data analysis, and the shortcomings are significantly improved. Starting with improving the equilibrium reconstruction that estimates the background magnetic field, adding a ripple correction in the reconstructed magnetic field profile, and adding new inner-wall reflection positions estimated through ray-tracing, these changes not only improve the agreement of reconstructed profiles to other diagnostics but also solve density profile wriggles that were present during band transitions. Other smaller but also persistent wriggles were also suppressed by applying a localized correction to the measured beat frequency where persistent oscillations are present. Finally, the burst analysis method, as introduced by Varela et\u00a0al. [Nucl. Fusion 46 S693 (2006)], has been implemented to extract the beat frequency from stacked spectrograms. Due to the strong suppression of spurious reflections, the radial jitter that sometimes would span several centimeters has been strongly reduced. The stacking of spectrograms has also been shown to be very useful for stacking recurring events, like small gas puff modulations, and extracting transport coefficients that would otherwise be below the noise level.<\/jats:p>","DOI":"10.1063\/5.0176696","type":"journal-article","created":{"date-parts":[[2024,4,1]],"date-time":"2024-04-01T12:47:33Z","timestamp":1711975653000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":11,"title":["Improved accuracy and robustness of electron density profiles from JET\u2019s X-mode frequency-modulated continuous-wave reflectometers"],"prefix":"10.1063","volume":"95","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0667-3356","authenticated-orcid":false,"given":"R. B.","family":"Morales","sequence":"first","affiliation":[{"name":"UKAEA (United Kingdom Atomic Energy Authority), Culham Campus 1 , Abingdon, Oxfordshire OX14 3DB, United Kingdom"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3306-6335","authenticated-orcid":false,"given":"A.","family":"Salmi","sequence":"additional","affiliation":[{"name":"VTT 2 , P.O. Box 1000, FI-02044 VTT Espoo, Finland"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2113-7922","authenticated-orcid":false,"given":"P.","family":"Abreu","sequence":"additional","affiliation":[{"name":"IPFN, Instituto Superior T\u00e9cnico da Universidade de Lisboa 3 , 1049-001 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7111-0619","authenticated-orcid":false,"given":"C. H. S.","family":"Amador","sequence":"additional","affiliation":[{"name":"Federal University of Technology\u2014Parana (UTFPR), Department of Natural Sciences 4 , Corn\u00e9lio Proc\u00f3pio, Brazil"}]},{"given":"L.","family":"Appel","sequence":"additional","affiliation":[{"name":"UKAEA (United Kingdom Atomic Energy Authority), Culham Campus 1 , Abingdon, Oxfordshire OX14 3DB, United Kingdom"}]},{"given":"P.","family":"Carman","sequence":"additional","affiliation":[{"name":"UKAEA (United Kingdom Atomic Energy Authority), Culham Campus 1 , Abingdon, Oxfordshire OX14 3DB, United Kingdom"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-4547-8292","authenticated-orcid":false,"given":"J.","family":"Fessey","sequence":"additional","affiliation":[{"name":"UKAEA (United Kingdom Atomic Energy Authority), Culham Campus 1 , Abingdon, Oxfordshire OX14 3DB, United Kingdom"}]},{"given":"J.","family":"Flanagan","sequence":"additional","affiliation":[{"name":"UKAEA (United Kingdom Atomic Energy Authority), Culham Campus 1 , Abingdon, Oxfordshire OX14 3DB, United Kingdom"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7979-7483","authenticated-orcid":false,"given":"M.","family":"Fontana","sequence":"additional","affiliation":[{"name":"UKAEA (United Kingdom Atomic Energy Authority), Culham Campus 1 , Abingdon, Oxfordshire OX14 3DB, United Kingdom"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9546-4494","authenticated-orcid":false,"given":"L.","family":"Frassinetti","sequence":"additional","affiliation":[{"name":"Division of Electromagnetic Engineering and Fusion Science, KTH 5 , Stockholm 100 44, Sweden"}]},{"given":"C.","family":"Giroud","sequence":"additional","affiliation":[{"name":"UKAEA (United Kingdom Atomic Energy Authority), Culham Campus 1 , Abingdon, Oxfordshire OX14 3DB, United Kingdom"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2104-9562","authenticated-orcid":false,"given":"S.","family":"Hacquin","sequence":"additional","affiliation":[{"name":"IRFM, CEA Cadarache 6 , 13108 Saint-Paul-lez-Durance, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7035-4574","authenticated-orcid":false,"given":"S.","family":"Heuraux","sequence":"additional","affiliation":[{"name":"IJL, University of Lorraine, UMR 7198 CNRS 7 , BP 50840, 54011 Nancy Cedex, France"}]},{"given":"L.","family":"Meneses","sequence":"additional","affiliation":[{"name":"ITER Organization 8 , Route de Vinon, CS 90 046, 13067 Saint-Paul-Lez-Durance, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3097-3033","authenticated-orcid":false,"given":"G.","family":"Ronchi","sequence":"additional","affiliation":[{"name":"Oak Ridge National Laboratory, Oak Ridge 9 , Tennessee, Tennessee 37830, USA"}]},{"given":"R.","family":"Sabot","sequence":"additional","affiliation":[{"name":"IRFM, CEA Cadarache 6 , 13108 Saint-Paul-lez-Durance, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0003-7263","authenticated-orcid":false,"given":"A.","family":"Silva","sequence":"additional","affiliation":[{"name":"IPFN, Instituto Superior T\u00e9cnico da Universidade de Lisboa 3 , 1049-001 Lisboa, Portugal"}]},{"given":"A.","family":"Sirinelli","sequence":"additional","affiliation":[{"name":"ITER Organization 8 , Route de Vinon, CS 90 046, 13067 Saint-Paul-Lez-Durance, France"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-9619-7976","authenticated-orcid":false,"given":"G.","family":"Szepesi","sequence":"additional","affiliation":[{"name":"UKAEA (United Kingdom Atomic Energy Authority), Culham Campus 1 , Abingdon, Oxfordshire OX14 3DB, United Kingdom"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0465-2466","authenticated-orcid":false,"given":"D.","family":"Taylor","sequence":"additional","affiliation":[{"name":"UKAEA (United Kingdom Atomic Energy Authority), Culham Campus 1 , Abingdon, Oxfordshire OX14 3DB, United Kingdom"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9339-283X","authenticated-orcid":false,"given":"D.","family":"Terranova","sequence":"additional","affiliation":[{"name":"Consorzio RFX and ISTP-CNR 10 , Corso Stati Uniti 4, 35127 Padova, Italy"}]}],"member":"317","published-online":{"date-parts":[[2024,4,1]]},"reference":[{"key":"2024040112472457600_c1","doi-asserted-by":"publisher","first-page":"10F108","DOI":"10.1063\/1.2972134","article-title":"First density profile measurements using frequency modulation of the continuous wave reflectometry on JET","volume":"79","year":"2008","journal-title":"Rev. Sci. Instrum."},{"key":"2024040112472457600_c2","doi-asserted-by":"publisher","first-page":"10D939","DOI":"10.1063\/1.3502329","article-title":"Multiband reflectometry system for density profile measurement with high temporal resolution on JET tokamak","volume":"81","year":"2010","journal-title":"Rev. Sci. Instrum."},{"key":"2024040112472457600_c3","article-title":"Profile reflectometry upgrade on JET"},{"key":"2024040112472457600_c4","unstructured":"H.\n            Bottollier-Curtet\n          , \u201cR\u00e9flectom\u00e9trie hyperfr\u00e9quence pour la d\u00e9termination de la densit\u00e9 \u00e9lectronique et de ses fluctuations sur le tokamak Petula-B,\u201d Ph.D. thesis, Universit\u00e9 de Paris XI, 1986."},{"key":"2024040112472457600_c5","article-title":"X-mode lower cutoff high field side reflectometer for electron density profile measurements in T-10 tokamak"},{"key":"2024040112472457600_c6","doi-asserted-by":"publisher","first-page":"043503","DOI":"10.1063\/1.4979513","article-title":"New density profile reconstruction methods in X-mode reflectometry","volume":"88","year":"2017","journal-title":"Rev. Sci. Instrum."},{"key":"2024040112472457600_c7","article-title":"An X-mode reflectometry study on the reflection point for the density profile reconstruction","year":"2009"},{"key":"2024040112472457600_c8","doi-asserted-by":"publisher","first-page":"905","DOI":"10.1088\/0741-3335\/38\/7\/002","article-title":"Reflectometry techniques for density profile measurements on fusion plasmas","volume":"38","year":"1996","journal-title":"Plasma Phys. Controlled Fusion"},{"key":"2024040112472457600_c9","doi-asserted-by":"publisher","first-page":"2201","DOI":"10.1063\/1.1149121","article-title":"Microwave reflectometry for magnetically confined plasmas","volume":"69","year":"1998","journal-title":"Rev. Sci. Instrum."},{"key":"2024040112472457600_c10","doi-asserted-by":"crossref","unstructured":"R. B.\n            Morales\n          , \u201cDensity profile reconstruction methods for extraordinary mode reflectometry,\u201d Ph.D. thesis, Universit\u00e9 de Lorraine, 2018.","DOI":"10.1063\/1.4979513"},{"key":"2024040112472457600_c11","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1016\/j.fusengdes.2014.09.019","article-title":"Tokamak equilibrium reconstruction code LIUQE and its real time implementation","volume":"91","year":"2015","journal-title":"Fusion Eng. Des."},{"key":"2024040112472457600_c12","article-title":"Time-dependent ELM-resolved equilibrium reconstruction on ASDEX Upgrade"},{"key":"2024040112472457600_c13","article-title":"Advanced equilibrium reconstruction for JET with EFIT++"},{"key":"2024040112472457600_c14","doi-asserted-by":"publisher","first-page":"3524","DOI":"10.1063\/1.1141562","article-title":"Broadband reflectometry for the density profile and fluctuation measurements in the JT-60 tokamak","volume":"61","year":"1990","journal-title":"Rev. Sci. Instrum."},{"key":"2024040112472457600_c15","doi-asserted-by":"publisher","first-page":"311","DOI":"10.1088\/1009-0630\/16\/4\/02","article-title":"Density profile and fluctuation measurements by microwave reflectometry on EAST","volume":"16","year":"2014","journal-title":"Plasma Sci. Technol."},{"key":"2024040112472457600_c16","doi-asserted-by":"publisher","first-page":"1807","DOI":"10.1063\/1.1146978","article-title":"Amplitude modulated heterodyne reflectometer for density profile and density fluctuation profile measurements at W7-AS","volume":"67","year":"1996","journal-title":"Rev. Sci. Instrum."},{"key":"2024040112472457600_c17","doi-asserted-by":"publisher","first-page":"74","DOI":"10.1063\/1.1150164","article-title":"Ultrafast frequency sweep heterodyne reflectometer on the Tore Supra tokamak","volume":"71","year":"2000","journal-title":"Rev. Sci. Instrum."},{"key":"2024040112472457600_c18","doi-asserted-by":"publisher","first-page":"083502","DOI":"10.1063\/1.3622747","article-title":"New signal processing technique for density profile reconstruction using reflectometry","volume":"82","year":"2011","journal-title":"Rev. Sci. Instrum."},{"key":"2024040112472457600_c19","doi-asserted-by":"publisher","first-page":"S677","DOI":"10.1088\/0029-5515\/46\/9\/s03","article-title":"Fast automated analysis of high-resolution reflectometer density profiles on DIII-D","volume":"46","year":"2006","journal-title":"Nucl. Fusion"},{"key":"2024040112472457600_c20","doi-asserted-by":"publisher","first-page":"1229","DOI":"10.1063\/1.1146012","article-title":"Advances in reflectometric density profile measurements on the DIII-D tokamak","volume":"66","year":"1995","journal-title":"Rev. Sci. Instrum."},{"key":"2024040112472457600_c21","doi-asserted-by":"publisher","first-page":"466","DOI":"10.1063\/1.1147607","article-title":"Development of a fast solid-state high-resolution density profile reflectometer system on the DIII-D tokamak","volume":"68","year":"1997","journal-title":"Rev. Sci. Instrum."},{"key":"2024040112472457600_c22","doi-asserted-by":"crossref","unstructured":"N. A.\n            Uckan\n          , T.Uckan, and J. R.Moore, \u201cCalculation of magnetic field ripple effects in circular and noncircular tokamaks,\u201d Master thesis, Oak Ridge National Laboratory, 1976.","DOI":"10.2172\/7348638"},{"key":"2024040112472457600_c23","article-title":"Gas scan to probe fuelling through the H-mode pedestal in JET"},{"key":"2024040112472457600_c24","doi-asserted-by":"publisher","first-page":"S693","DOI":"10.1088\/0029-5515\/46\/9\/s05","article-title":"Review of data processing techniques for density profile evaluation from broadband FM-CW reflectometry on ASDEX Upgrade","volume":"46","year":"2006","journal-title":"Nucl. Fusion"},{"key":"2024040112472457600_c25","doi-asserted-by":"publisher","first-page":"100599","DOI":"10.1016\/j.nme.2019.02.002","article-title":"Using EDGE2D-EIRENE to simulate the effect of impurity seeding and fueling on the upstream electron separatrix temperature","volume":"20","year":"2019","journal-title":"Nucl. Mater. Energy"},{"key":"2024040112472457600_c26","unstructured":"M.\n            Colin\n          , \u201cModelisations d\u2019un reflectometre mode X en vue de caracteriser les fluctuations de densite et de champ magnetique: Applications aux signaux de Tore Supra,\u201d Ph.D. thesis, Universit\u00e9 de Lorraine, 2001."},{"key":"2024040112472457600_c27","doi-asserted-by":"publisher","first-page":"307","DOI":"10.3934\/dcdss.2012.5.307","article-title":"Simulations on wave propagation in fluctuating fusion plasmas for reflectometry applications and new developments","volume":"5","year":"2012","journal-title":"Discrete Contin. Dyn. Syst. S"},{"key":"2024040112472457600_c28","first-page":"704","article-title":"Runge-Kutta method, section\u00a016.1","volume-title":"Numerical Recipes in FORTRAN: The Art of Scientific Computing","year":"1992","edition":"2nd ed."},{"key":"2024040112472457600_c29","doi-asserted-by":"publisher","first-page":"3530","DOI":"10.1109\/78.340790","article-title":"A simple scheme for adapting time-frequency representations","volume":"42","year":"1994","journal-title":"IEEE Trans. Signal Process."},{"key":"2024040112472457600_c30","doi-asserted-by":"publisher","first-page":"044003","DOI":"10.1088\/1361-6587\/acbb23","article-title":"Pedestal particle balance studies in JET-ILW H-mode plasmas","volume":"65","year":"2023","journal-title":"Plasma Phys. Controlled Fusion"},{"key":"2024040112472457600_c31","doi-asserted-by":"publisher","first-page":"112009","DOI":"10.1088\/1741-4326\/acf057","article-title":"Effect of the isotope mass on pedestal structure, transport and stability in D, D\/T and T plasmas at similar \u03b2N and gas rate in JET-ILW type I ELMy H-modes","volume":"63","year":"2023","journal-title":"Nucl. Fusion"},{"key":"2024040112472457600_c32","article-title":"Comparison of particle transport and confinement properties between the ICRH and NBI heated dimensionless identity plasmas on JET"},{"key":"2024040112472457600_c33","doi-asserted-by":"publisher","first-page":"066008","DOI":"10.1088\/1741-4326\/ac5667","article-title":"Role of NBI fuelling in contributing to density peaking between the ICRH and NBI identity plasmas on JET","volume":"62","year":"2022","journal-title":"Nucl. Fusion"},{"key":"2024040112472457600_c34","doi-asserted-by":"publisher","first-page":"112012","DOI":"10.1088\/1741-4326\/acea94","article-title":"Isotope mass scaling and transport comparison between JET deuterium and tritium L-mode plasmas","volume":"63","year":"2023","journal-title":"Nucl. Fusion"},{"key":"2024040112472457600_c35","article-title":"Gas scan to probe fuelling through the H-mode pedestal in JET"},{"key":"2024040112472457600_c36","doi-asserted-by":"publisher","first-page":"055025","DOI":"10.1088\/1361-6587\/acc425","article-title":"Electron density pedestal behaviour in strike-point sweeping experiment on JET","volume":"65","year":"2023","journal-title":"Plasma Phys. Controlled Fusion"},{"key":"2024040112472457600_c37","doi-asserted-by":"publisher","first-page":"112015","DOI":"10.1088\/1741-4326\/aceb08","article-title":"Experiments in high-performance JET plasmas in preparation of second harmonic ICRF heating of tritium in ITER","volume":"63","year":"2023","journal-title":"Nucl. Fusion"},{"key":"2024040112472457600_c38","first-page":"(unpublished)","article-title":"Characterisation of the SOL conditions and detachment in JET-ILW hydrogen, deuterium and tritium low-confinement mode plasmas","year":"2024"},{"key":"2024040112472457600_c39","article-title":"Control of plasma density and isotope mix by peripheral fuelling pellets in JET D-T experiments","year":"2024","journal-title":"Nucl. Fusion"},{"key":"2024040112472457600_c40","article-title":"Development of high current baseline scenario for high deuterium-tritium fusion performance at JET","year":"2024"},{"key":"2024040112472457600_c41","doi-asserted-by":"publisher","first-page":"126057","DOI":"10.1088\/1741-4326\/ac97f4","article-title":"Effect of the divertor configuration on the JET edge radial electric field","volume":"62","year":"2022","journal-title":"Nucl. Fusion"},{"key":"2024040112472457600_c42","doi-asserted-by":"publisher","first-page":"112011","DOI":"10.1088\/1741-4326\/acee12","article-title":"L-H transition studies in tritium and deuterium\u2013tritium campaigns at JET with Be wall and W divertor","volume":"63","year":"2023","journal-title":"Nucl. Fusion"}],"container-title":["Review of Scientific Instruments"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.aip.org\/aip\/rsi\/article-pdf\/doi\/10.1063\/5.0176696\/19863459\/043501_1_5.0176696.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.aip.org\/aip\/rsi\/article-pdf\/doi\/10.1063\/5.0176696\/19863459\/043501_1_5.0176696.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,4,1]],"date-time":"2024-04-01T12:47:45Z","timestamp":1711975665000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.aip.org\/rsi\/article\/95\/4\/043501\/3280402\/Improved-accuracy-and-robustness-of-electron"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,4,1]]},"references-count":42,"journal-issue":{"issue":"4","published-print":{"date-parts":[[2024,4,1]]}},"URL":"https:\/\/doi.org\/10.1063\/5.0176696","relation":{},"ISSN":["0034-6748","1089-7623"],"issn-type":[{"value":"0034-6748","type":"print"},{"value":"1089-7623","type":"electronic"}],"subject":[],"published-other":{"date-parts":[[2024,4,1]]},"published":{"date-parts":[[2024,4,1]]},"article-number":"043501"}}